Designation: D1129 − 13

Standard Terminology Relating toWater1

This standard is issued under the fixed designation D1129; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (´) indicates an editorial change since the last revision or reapproval.

absolute filter rating, n—particle size above which 100 % ofparticles that are trapped on or within the filter medium.

D6161

absorbance, n—logarithm to the base 10 of the reciprocal ofthe transmittance (T). A = log10 (1/ T) = –log10 T. D4691

absorption, n—release for desorption holding of a substancewithin a solid by cohesive or capillary forces. D6161

absorptivity, n—absorbance (A) divided by the product of thesample path length (b) and the concentration (c). a = A/bc.

D4691

accelerated erosion, n—erosion at a rate greater than geologicor natural erosion. D4410

DISCUSSION—Accelerated erosion is usually associated with anthro-pogenic activities and usually reduces plant cover and increases runoff.

acceptable holding time, n—any period of time less than orequal to the maximum holding time. D4841

acceptable verification ratio (AVR)—ratio of the differencebetween measured value of the verification sample and theknown value added to the verification sample to the squareroot of the sum of the squares of their associated combinedstandard uncertainties. See Eq. 8 in 16.2.13. D7282

accretion, n—process of sediment accumulation. D4410

accumulator, n—pulsation dampener installed on the suctionand/or discharge lines of pumps, generally plunger type, tominimize pressure surges and provide uniformity of flow.

D6161

accuracy, n—a measure of the degree of conformity of a valuegenerated by a specific procedure to the assumed or acceptedtrue value, and includes both precision and bias.

accuracy, n—closeness of agreement between an observedvalue and an accepted reference value. Where an acceptedreference value is not available, accuracy is a description ofa measure of the degree of conformity of a value generated

by a specific procedure to the assumed or accepted truevalue, including both precision and bias. D6161

accuracy, n—measure of the degree of conformity of a singletest result generated by a specific procedure to the assumedor accepted true value, and includes both precision and bias.

D2777

accuracy, n—proportion of the observed count to the truedensity of a sample. D5392

accuracy, n—refers to how close a measurement is to the trueor actual value. (See Terminology D1129.) D5906

acid error, n—in very acid solutions, the activity of water isreduced (less than unity) causing a non-Nernstian responsein glass electrodes. A positive error in the pH reading results.

D4127

acidity, n—the quantitative capacity of aqueous media to reactwith hydroxyl ions.

acidity, n—quantitative capacity of aqueous media to reactwith hydroxyl ions. D6161

acidity, free mineral, n—the quantitative capacity of aqueousmedia to react with hydroxyl ions to pH 4.3.

acidity, theoretical free mineral, n—the free mineral aciditythat would result from the conversion of the anions of strongacids in solution to their respective free acids.

acoustic path, n—straight line between the centers of twoacoustic transducers. D5389

acoustic path length, n—face-to-face distance between trans-ducers on an acoustic path. D5389

acoustic transducer, n—device that is used to generate acous-tic signals when driven by an electric voltage, andconversely, a device that is used to generate an electricvoltage when excited by an acoustic signal. D5389

acoustic travel time, n—time required for an acoustic signal topropagate along an acoustic path, either upstream ordownstream. D5389

action level, n—concentration of the analyte of concern atwhich some further action is required or suggested. D6850

1 This terminology is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.02 on Quality Systems,Specification, and Statistics.

Current edition approved March 1, 2013. Published April 2013. Originallyapproved in 1950. Last previous edition approved in 2010 as D1129 – 10. DOI:10.1520/D1129-13.

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

1

http://www.astm.org/COMMIT/COMMITTEE/D19.htmhttp://www.astm.org/COMMIT/SUBCOMMIT/D1902.htm

activated carbon, n—granulated or powdered activated carbonused to remove tastes, odor, chlorine, chloramines, and someorganics from water. A family of carbonaceous substancesmanufactured by processes that develop adsorptiveproperties. D6161

activity, n—thermodynamically effective concentration of afree ion in solution. In dilute solutions, ionic activity andconcentration are practically identical, but in solutions ofhigh ionic strength, or in the presence of complexing agents,activity may differ significantly from concentration. Ionicactivity, not concentration, determines both the rate and theextent of chemical reactions. D4127

activity coefficient, n—factor, γ, that relates activity, A, to theconcentration, C of a species in solution:

A 5 γC

The activity coefficient is dependent on the ionic strengthof the solution. Ions of similar size and charge have similaractivity coefficients. D4127

activity standard, n—standardizing solution whose value isreported in terms of ionic activity. If the electrode iscalibrated using activity standards, the activity of the free,unbound ion in the sample is determined. D4127

adenosine triphosphate—see ATP. D6161

adsorption, n—holding of a substance onto the surface of asolid by chemical surface forces, without forming newchemical bonds. D6161

aerobic bacteria, n—bacteria that require oxygen for growth.See bacteria, aerobes. D6161

aerosol, n—any solid or liquid particles, with a nominal sizerange from 10 nm to 100 µm, suspended in a gas (usuallyair). D5544

agglomeration or flocculation, n—coalescence of dispersedsuspended matter into large flocs or particles that settlerapidly. D4410

aggradation, n—geologic process by which stream beds, floodplains, and the bottoms of other water bodies are raised inelevation by the deposition of material eroded and trans-ported by water from other areas. D4410

aggregate, n—granular material such as sand, gravel, orcrushed stone. D6161

air header, n—pipe running within a cassette that distributesthe air to the individual modules or aerators. D6161

air scour, v—distributing air over the entire area at the bottomof a filter media flowing upward or immersed membrane toimprove the effectiveness of filtration or backwashing or topermit the use of lower backwash water flow rate, or both.

D6161

air stripping, v—removal of volatile substances from a watersolution by passing a gas through the solution. D6161

algae, n—major group of lower plants, generally aquatic,photosynthetic of extremely varied morphology and

physiology, monocellular plants with chlorophyll oftenmasked by a brown or red pigment. D6161

alkaline error, n—in alkaline solutions, where hydrogen ionactivity becomes very small, some glass electrodes respondto other cations, such as sodium. A negative error in the pHreading results. By changing the composition of the glass,the affinity of the glass for sodium ion can be reduced. Suchelectrodes are known as lithium glass, high-pH, or full-rangeelectrodes. D4127

alkalinity, n—the quantitative capacity of aqueous media toreact with hydrogen ions.

alkalinity, n—quantitative capacity of aqueous media to reactwith hydrogen ions. “M” alkalinity is that which will reactwith acid as the pH of the sample is reduced to themethylorange endpoint of about 4.5. “P” alkalinity is thatwhich reacts with acid as the pH of the sample is reduced tothe phenolphthalein end point of 8.3. “M” is the totalalkalinity which is the sum of hydroxide, carbonate, andbicarbonate contents, “P” includes all the hydroxyl and halfthe carbonate content. D6161

alkyl benzene sulfonate (ABS)2—generic name applied to theneutralized product resulting from the sulfonation of abranched-chain alkylated benzene. See also TerminologyD459. D2330

alluvial channel—see alluvial stream. D4410

alluvial deposit—sediment deposited by the action of movingwater. D4410

alluvial fans—sediment deposited in the shape of a segment ofa cone formed because of a sudden flattening of a streamgradient especially at debouchures of tributaries on mainstream flood plains. D4410

alluvial stream, n—stream whose boundary is composed ofappreciable quantities of the sediments transported by theflow and which generally changes its bed forms as the rate offlow changes. D4410

alleviation, n—process of accumulating sediment deposits atplaces where the flow is retarded. D4410

alluvium, n—general term for all fluvial deposits resultingdirectly or indirectly from the sediment transport of (mod-ern) streams, thus including the sediments laid down inriverbeds, flood plains, lakes, fans, and estuaries. D4410

alpha (α), n—velocity-head coefficient that adjusts the velocityhead computed on basis of the mean velocity to the truevelocity head. D5129

alpha (α), n—velocity-head coefficient that adjusts the velocityhead computed on basis of the mean velocity to the truevelocity head. It is assumed equal to 1.0 if the cross sectionis not subdivided. D5243

2 For a more complete discussion of terms relating to synthetic detergents andtheir significance, refer to “Syndets and Waste Disposal” by McKinney, R. E.,Sewage and Industrial Wastes, Vol 29, Part 6, June 1957, pp. 654-666.

D1129 − 13

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alpha (α), n—velocity-head coefficient that represents the ratioof the true velocity head to the velocity head computed onthe basis of the mean velocity. It is assumed equal to 1.0 ifthe cross section is not subdivided. For subdivided sections,a is computed as follows: D5130

α 5( S ki3Ai2D

KT3

AT2

where:K and A = the conveyance and area of the subsection

indicated by the subscript i andKT and AT = the conveyance and area of the entire cross

section.

alpha (α), n—dimensionless velocity-head coefficient thatrepresents the ratio of the true velocity head to the velocityhead computed on the basis of the mean velocity. It isassumed equal to unity if the cross section is not subdivided.For subdivided sections, a is computed as follows: D5388

α 5( S ki3ai2D

KT3

AT2

where:k and a = the conveyance and area of the subsection

indicated by the subscript i andKT and AT = the conveyance and area of the total cross

section indicated by the subscript T.

alpha particle (α), n—particle consisting of two protons andtwo neutrons emitted from the nucleus of an atom duringradioactive decay. D7316

alpha particle detection efficiency, n—in the measurement ofradioactivity, that fraction of alpha particles emitted by asource which are identified as alpha particles by the counter.

D7283

alpha-to-beta spillover, n—in the measurement ofradioactivity, that fraction of alpha particles emitted by asource which are misclassified as beta particles. D7283

alum, n—aluminum sulfate, AL2(SO4)3XH2O (X = 14-18), acoagulant. D6161

ambient temperature, n—temperature of the surroundings,generally assumed to be 20–25°C. D6161

American Water Works Association—see AWWA. D6161

American Water Works Association ResearchFoundation—see AWWARF. D6161

amorphous, adj—noncrystalline, devoid of regular cohesivestructure. D6161

amperometric systems, n—those instrumental probes thatinvolve the generation of an electrical current from whichthe final measurement is derived. D888

amphoteric, adv—capable of acting as an acid or a base.D6161

anaerobic bacteria, n—bacteria that do not use oxygen.Oxygen is toxic to them. See bacteria, anaerobes. D6161

analate addition, n—variation of the known addition measure-ment technique in which the sample (analate) is added to areagent containing the ion being measured. The electrode isplaced in the reagent, and the sample concentration iscalculated from the change in electrode potential after theaddition of the sample. D4127

analate subtraction, n—variation of the known subtractionmeasurement technique in which the sample (analate) isadded to a reagent containing an ion that reacts with thespecies being determined. The electrode is placed in thereagent, the change in electrode potential is observed whenthe sample is added, and the sample concentration calcu-lated. D4127

analyte, n—a possible sample component whose presence andconcentration is of interest.

analyte, n—chemical or constituent being determined. D5463

analytical column, n—chromatography column that containsthe stationary phase for separation by ion exchange. Thecolumn is packed with anion exchange resin that separatesthe analytes of interest based on their retention characteris-tics before detection. D6994

analytical column, n—column used to separate the anions ofinterest. D5996

analytical column, n—ion exchange column used to separatethe ions of interest according to their retention characteristicsprior to detection. D6581

analytical column set, n—combination of one or more guardcolumns, followed by one or more analytical columns usedto separate the ions of interest. All of the columns in seriesthen contribute to the overall capacity and resolution of theanalytical column set. D6581

analytical column set, n—combination of one or more guardcolumns followed by one or more analytical columns.

D5996

analytical columns, n—combination of one or more guardcolumns followed by one or more separator columns used toseparate the ions of interest. It should be remembered that allof the columns in series contribute to the overall capacity ofthe analytical column set. D4327

analytical columns, n—combination of one or more guardcolumns followed by one or more separator columns used toseparate the ions of interest. It should be remembered that allof the columns in series contribute to the overall capacity ofthe analytical column set. D5542

analyze, v—to determine the relationship of parts or the valueof a particular parameter. D5851

analyzer—see monitoring system. D3864

angstrom (A), n—unit of length equaling 10-10 metres, 10-4

umetres, 10-8 centimetres, and 3.937 × 10-9 in. The symbolis Å, A, or A.U. D6161

D1129 − 13

3

animal/vegetable-derived oils, n—mixture made of mono-,di-, and triglyceride esters of fatty acids and other substancesof animal or vegetable origin, or both. D3326

anion, n—negatively charged ion. D6161

anion exchange chromatography, n—type of liquid chroma-tography in which anionic analytes are separated by differ-ential retention on an anion exchange resin and detected byan appropriate detection mechanism. D6994

anion-exchange material, n—a material capable of the revers-ible exchange of negatively charged ions.

anion-exchange material, n—ion-exchange material capableof the reversible exchange of negatively charged ions.

D2187

anion-exchange material, n—ion-exchange material capableof the reversible exchange of negatively charged ions.

D4548

anion exchange material, n—material capable of the revers-ible exchange of negatively charged ions. D6161

anion exchange membrane, n—membrane containing fixedcationic charges and mobile anions that can be exchangedwith other anions present in an external fluid in contact withthe membrane. D6161

anion suppressor device, n—device that is placed between theanalytical columns and the detector. Its purpose is to inhibitdetector response to the ionic constituents in the eluant so asto lower the detector background and at the same timeenhance detector response to the ions of interest. D5996

anion trap column, n—high-capacity, low-pressure anionexchange column used to remove reagent impurities fromthe eluent stream. The anion trap column is placed betweenthe eluent reservoir and the gradient pump. D6994

anionic polyelectrolyte, n—usually acrylamide or acrylamideand acrylic copolymers, negatively charged, used forcoagulation/flocculation. See polyelectrolyte. D6161

anisotropic, adv—having different optical properties in differ-ent optical planes. These planes are referred to as the alpha,beta, and omega axes. D1245

anisotropic membrane, n—nonuniform structure in crosssection; typically the support substructure has pores muchlarger than the barrier layer. See asymmetric membranes.

D6161

anode, n—positive electrode. D6161

anthracite, n—granular hard coal used as a filtration media,commonly used as the coarser layer in dual and multimediafilters. D6161

antidunes, n—bed forms that occur at a velocity higher thanthat velocity that forms dunes and plane beds. Antidunescommonly move upstream, and are accompanied by, and inphase with, waves on the water surface. D4410

antifoulant, n—see antiscalant . D6161

antiscalant, n—compound added to a water that inhibits theprecipitation of sparingly soluble inorganic salts. D6161

anti-telescoping device, n—plastic or metal device attached tothe ends of a spiral wound cartridge to prevent movement ofthe cartridge leaves in the feed flow direction as a result ofhigh feed flows. D6161

approach angle, n—angle between the velocity vector of theapproaching flow and the centerline of the nozzle. D6326

approaching flow, n—flow immediately upstream of a nozzlesentrance. D6326

aquatic free cyanide, n—sum of the free cyanide (HCN andCN-) and cyanide bound in the metal-cyanide complexes thatare easily dissociated into free cyanide under the testconditions described in this method. D7237

aquifer, n—geologic formation containing water, usually ableto yield appreciable water. D6146

aquifer, n—water-bearing geological formation that provides aground water reservoir. D6161

aramid, n—fully aromatic polyamide. D6161

area (A), n—area of a cross section, parts of a cross section, orparts of bridges below the water surface. Subscripts indicatespecific areas as follows: D5129

Ai = area of subsection i,Aj = area of piers or piles that is submerged,A1 = area of total cross-section 1 (see Fig. 1 of D5129), andA3 = gross area of Section 3 of D5129.

armoring, v—formation of a resistant layer of relatively largeparticles by erosion of the finer particles. D4410

array, n—arrangement of devices connected to common feed,product, and reject headers; that is, a 2:1 array. D6161

assess, v—to determine importance of data. D5851

assess, v—to determine the significance, value, and importanceof the data collected and recorded. D6145

assimilable organic carbon, n—see AOC. D6161

asymmetric membrane, n—membrane that has a change inpore structure. See anisotropic membranes. D6161

asymmetry potential, n—potential across a glass pH electrodemembrane when the inside and outside of the membrane arein contact with solutions of identical pH. This term has alsobeen used to define the observed potential differencesbetween identical electrode pairs placed in identical solu-tions. D4127

atomic absorption, n—absorption of electromagnetic radia-tion by an atom resulting in the elevation of electrons fromtheir ground states to excited states. Atomic absorptionspectrophotometry involves the measurement of light ab-sorbed by atoms of interest as a function of the concentrationof those atoms in a particular solution. D4691

D1129 − 13

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automatic programmable sampler, n—portable device de-signed to collect sequential, discrete water samples repre-sentative of the water mixture moving in the river in thevicinity of the sampler at a single point in a cross section.Depending on the make and model of the device, watersamples can be collected at equal or variable time intervals.

D5613

autopsy, n—dissection of a membrane module or element toinvestigate causes of unsatisfactory performance. D6161

available cyanide—inorganic cyanides that are free (HCN andCN-) and metal-cyanide complexes that are easily dissoci-ated into free cyanide ions. Available cyanide does notinclude the less toxic strong metal-cyanide complexes,cyanides that are not “amenable to chlorination.” D6888

availability, n—on-stream time or rated operating capacity ofa water treatment system. D6161

a-value, n—membrane water permeability coefficient. Thecoefficient is defined as the amount of water produced perunit area of membrane per unit of net driving pressure(NDP); units of measurement are m3/h/m2/kPa. D6161

avulsion, n—sudden, natural change of a stream channel, sothat the water flows elsewhere than in its previous course.

D4410

B-value—salt diffusion coefficient, n—defined as the amountof salt transferred per unit area of membrane per unit ofconcentration difference across the membrane. A unit ofmeasurement is m/h or more specifically, m3/m2/h. D6161

back pressure regulator—a device designed to maintain aconstant pressure upstream of itself (variable or fixed backpressure regulators are available) to maintain constant flowin analyzers in continual sampling. D3370

back titration, n—see titration . D4127

backflush, n—temporary reversal of the permeate or retentateflow. D6161

background sample, n—sample taken from a location on orproximate to the site of interest. This sample is taken todocument baseline or historical information. D5612

background subtraction count (BSC)—a source count usedto determine the background to be subtracted from thesample test source count. D7282

backpulse, n—pumping treated water with or without addedchemicals in the reversed direction from the lumen to thefeed side of the membrane (inside out). D6161

backwash, n—reversing the flow of water with/without aireither across or through a medium or membrane. Designedto remove the collected foreign material from the bed ormembranes. D6161

bacteria, n—any of a class of microscopic single-celledorganisms reproducing by fission or by spores. Character-ized by round, rod-like, spiral, or filamentous bodies, oftenaggregated into colonies or mobile by means of flagella.

Widely dispersed in soil, water, organic matter, and thebodies of plants and animals. Either autotrophic (self-sustaining, self-generative), saprophytic (derives nutritionfrom nonliving organic material already present in theenvironment), or parasitic (deriving nutrition from anotherliving organism). Often symbiotic (advantageous) in man,but sometimes pathogenic. D6161

bacterial lawn, n—confluent growth of bacteria cultured on anagar plate. D6734

bactericide, n—agent capable of killing bacteria. D6161

bacteriostat, n—substance that prevents bacterial growth andmetabolism but does not necessarily kill them. D6161

baffle, n—deflector plate in a vessel that disperses the inletfluid. D6161

bag sampler—a sampler that uses a collapsible bag as thesample collection container. D4410

bank, n—grouping of devices. See array, block, train. D6161

bar, n—section of metallic channel, I-beam, T-beam, pipe,plate, or ball that will reflect sound waves produced by afathometer. D6318

bar, n—unit of pressure; 14.50 lbs/in.2, 1.020 kg/cm2, 0.987atm, 0.1 MPa. D6161

bar-check, n—method for calibrating a fathometer by setting asound or acoustic reflector (bar) below a survey vessel to aknown depth below a sounding transducer. D6318

bar-check, n—method for determining depth below a surveyvessel by means of a long, narrow metal bar or beamsuspended on a marked line beneath a sounding transducer.

D5073

bar sweep, n—bar or pipes, suspended by wire or cablebeneath a floating vessel, used to search for submerged snagsor obstructions hazardous to navigation. D5073

base flow, n—stream flow that is sustained by ground waterand other delayed sources. D4410

batch, n—in the analysis of water, a group of samples to beanalyzed, assembled in such a way that all the variablesaffecting the batch will affect all the samples and standardsin the batch in a statistically equivalent manner.

DISCUSSION—Batching is a fundamental quality-control component.With properly constructed batches, the results of quality controlelements can be used reliably to identify out-of-control situations in theanalytical system and to assign uncertainty to individual results fromthe batch.

batch, adj—in the analysis of water, characterizing standardsthat are carried through all of the analytical steps attached tothe analytical method being employed.

batch, n—set (group) of samples analyzed such that results ofanalysis of the QC samples (laboratory control sample,method blank, matrix spike, and duplicate or matrix spikeduplicate) analyzed with the batch are indicative of thequality of the results of analysis of samples in the batch. The

D1129 − 13

5

number of samples in the batch is defined by the task groupresponsible for the method. See 6.4 and Explanation 2 inAppendix X1 of Practice D5847. D5847

DISCUSSION—When results from tests of any of the QC samplesassociated with the batch fail to meet the performance criteria, the testmethod should define the appropriate corrective action. To make sucha response valid, the batch shall be constructed in such a way as toassure that all variables affecting the batch will affect all samples in thebatch in a statistically equivalent manner.

batch, n—set (group) of samples analyzed such that results ofanalysis of the QC samples analyzed with the batch areindicative of the quality of the results of analysis of samplesin the batch. The number of samples in the batch is definedby the task group responsible for the method. D6850

DISCUSSION—See Practice D5847 for definition and discussion ofbatch and batch size.

baseline, n—primary reference line for use in measuringazimuth angles and positioning distances. D5906

baume scale, Be, n—measure of the density of a solutionrelative to water. D6161

BE 5 145 2145

specific gravity*

United States for densities greater than unity.

BE 5140

specific gravity*2 130

For densities less than unity.*at 60°F

beam width, n—angle in degrees made by the main lobe ofacoustical energy emitted from the radiating face of atransducer. D5073

Becke line, n—faint, halo-like line that surrounds a crystalwhen the crystal is mounted in an oil of different refractiveindex. It increases in intensity as the difference in therefractive index between the crystal and the oil increases.

D1245

Becquerel, n—unit of radioactivity equivalent to one nucleartransformation per second. D1890

bed depth, n—depth of the filter medium or ion exchange resinin a vessel. D6161

bed expansion, n—depth increase of filter medium or ionexchange resin that occurs during backwashing. D6161

bed-load, n—material moving on or near the stream bed byrolling, sliding, and skipping. D4410

bed-load discharge, n—quantity of bed-load passing a crosssection of a stream in a unit of time. D4410

bed-load sampler, n—device for sampling the bed-load.D4410

bed material, n—sediment mixture of which the stream bed iscomposed. D4410

bed-material discharge, n—that part of the total sedimentdischarge composed of grain sizes occurring in appreciablequantities in the bed material. D4410

bed-material load, n—that part of the total load which iscomposed of particle sizes present in appreciable quantitiesin the shifting portions of the stream bed. D4410

best available technology—see BAT. D6161

best management practice (BMP), n—practice or combina-tion of practices that are determined by state or area-wideplanning agencies to be the most effective and practicalmeans of controlling point and nonpoint pollution. D6145

beta energy, maximum, n—maximum energy of the beta-particle energy spectrum produced during beta decay of agiven radioactive species. D1890

DISCUSSION—Since a given beta-particle emitter may decay to severaldifferent quantum states of the product nucleus, more than onemaximum energy may be listed for a given radioactive species.

beta energy, maximum, n—the maximum energy of the betaparticle energy spectrum produced during beta decay of agiven radionuclide.

DISCUSSION—Since a given beta emitter may decay to severaldifferent nuclear energy levels of the progeny, more than one maximumenergy may be listed for a given radionuclide. D7283

beta particle (β), n—electron or positron emitted from thenucleus of an atom during radioactive decay. D7316

beta particle detection efficiency, n—in the measurement ofradioactivity, that fraction of beta particles emitted by asource which are identified as beta particles by the counter.

D7283

beta-to-alpha spillover, n—in the measurement ofradioactivity, that fraction of beta particles emitted by asource which are misclassified as alpha particles. D7283

bias, n—the persistent positive or negative deviation of themethod average value from the assumed or accepted truevalue.

bias, n—persistent positive or negative deviation of the aver-age value of a test method from the assumed or accepted truevalue. D2777

bias, n—persistent positive or negative deviation of the aver-age value of the test method from the assumed or acceptedtrue value. D5392

binders, n—in reference to cartridge filters, chemicals used tohold, or “bind,” short fibers together in a filter. D6161

binding, n—in surface filtration, a buildup of particulates onthe filter, restricting fluid flow through the filter at normalpressures. D6161

biochemical oxygen demand (BOD), n—the quantity ofoxygen consumed in the biological and chemical oxidationof water-borne substances under conditions of test.

biocide, n—substance that kills all living organisms. D6161

biodegradable plastic, n—degradable plastic in which thedegradation results from the action of naturally occurringmicroorganisms such as bacteria, fungi, and algae. D6888

D1129 − 13

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biological deposits, n—deposits of organisms or the productsof their life processes.

biological deposits, n—debris left by organisms as a result oftheir life processes. D6161

biological deposits—water-formed deposits of organisms orthe products of their life processes. D887

biomass, n—any material that is or was a living organism orexcreted from a microorganism. D6161

bioremediation, n—biological degradation treatment of wastesludge and soils to breakdown organic and hydrocarbons.

D6161

biostat, n—substance that inhibits biological growth. D6161

bipolar membrane, n—synthetic membrane containing twooppositely charged ion-exchange layers that are in contactwith each other. D6161

blackwater, n—increase in the depth of flow upstream of achannel obstruction, in this case, a weir or flume. D5640

blank, n—matrix carried through all or part of the analyticalprocess, where the analyte is not present, or where theanalyte response is suppressed.

NOTE 1—A blank must be appropriate to the analytical process it isbeing used with.

NOTE 2—A blank is typically used to monitor contamination or toestablish a baseline for quantitation.

block, n—grouping of devices in a single unit having commoncontrol. See array, bank, train. D6161

BOD, n—biochemical oxygen demand.

body feed, v—continuous addition of filter medium (forexample, diatomaceous earth) to sustain the efficacy of thefilter. D6161

bottom profile, n—line trace of the bottom surface beneath awater body. D5073

bottomset bed, n—fine-grained material (usually silts andclays) slowly deposited on the bed of a quiescent body ofwater which may in time be buried by foreset beds and topsetbeds. D4410

boulder size (fluvial sediment), n—larger than 256 mm indiameter. D4410

boundary layer, n—relatively thin layer of viscous influenceadjacent to the probe (or any solid) surface caused by therequirement that the water velocity must be zero at the wall.

D5089

boundary layer, n—thin layer at the membrane surface wherewater velocities are significantly less than those in the bulkflow. D6161

boundary layer displacement thickness, n—boundary layeris a layer of fluid flow adjacent to a solid surface (in thiscase, the flume throat) in which, owing to viscous friction,the velocity increases from zero at the stationary surface toan essentially frictionless-flow value at the edge of the layer.

The displacement thickness is a distance normal to the solidsurface that the surface and flow streamlines can be consid-ered to have been displaced by virtue of the boundary-layerformation. D5390

boundary layer displacement thickness, n—boundary layeris a layer of fluid flow adjacent to a solid surface (in thiscase, the weir crest and sidewalls) in which, because ofviscous friction, the velocity increases from zero at thestationary surface to an essentially frictionless-flow value atthe edge of the layer. The displacement thickness is adistance normal to the solid surface that the flow streamlinescan be considered to have been displaced by virtue of theboundary-layer information. D5614

brackish water, n—water that contains dissolved matter at anapproximate concentration range from 1000 to 30 000 mg/L.

brackish water, n—water with an approximate concentrationof total dissolved solids ranging from 500 to 10 000 mg/L.See high brackish water, potable water, sea water. D6161

braided river, n—wide- and shallow-river where the flowpasses through a number of small interlaced channelsseparated by bars or shoals. D4410

brackish water reverse osmosis, n—see BWRO. D6161

breakpoint chlorination, n—point at which the water chlorinedemand is satisfied and any further chlorine is the chlorineresidual, the “free” chlorine species. D6161

break tank, n—storage device used for hydraulic isolation andsurge protection. D6161

breakthrough volume, n—maximum sample volume that canbe passed through a concentrator column before the leasttightly bound ion of interest is eluted. D5542

breakthrough volume, n—maximum sample volume that canbe passed through a concentrator column before the leasttightly bound ion of interest is eluted. All of the columns inseries contribute to the overall capacity of the analyticalcolumn set. D5996

brine, n—water that contains dissolved matter at an approxi-mate concentration of more than 30 000 mg/L.

brine, n—concentrate (reject) stream from a crossflow mem-brane device performing desalination. Portion of the feedstream that does not pass through the membrane. D6161

brine, n—water that contains dissolved matter at an approxi-mate concentration of more than 30 000 mg/L. D1429

brine (concentrate) seal, n—rubber lip seal on the outside ofa spiral wound cartridge that prevents feed by-pass betweenthe cartridge and the inside pressure vessel wall. D6161

brine seal carrier, n—see ATD. D6161

brine system staging, n—process in which the concentrate,under pressure, of a group of membrane devices is feddirectly to another set of membrane devices to improve theefficiency of the water separation. D6161

D1129 − 13

7

bubble point, n—pressure differential at which bubbles firstappear on one surface of an immersed porous membrane asgas pressure is applied to the other side. D6161

bubble point, n—when the pores of a membrane are filled withliquid and air pressure is applied to one side of themembrane, surface tension prevents the liquid in the poresfrom being blown out by air pressure below a minimumpressure known as the bubble point. D6908

bubble point pressure, n—pressure differential necessary todisplace a liquid held by surface tension forces from thelargest equivalent capillaries in a membrane filter. D6161

bubble point test, n—nondestructive membrane filter test usedto assess filter integrity and proper installation. D6161

buffer, n—substance in solution that accepts hydrogen orhydroxyl ions added to the solution minimizing a change inpH. D6161

build, own, operate—see BOO. D6161

build, own, operate and transfer—see BOOT. D6161

bundle, n—general term for a collection of parallel filamentsor fibers. D6161

cage, n—structural fabrication fitted around the perimeter ofthe cassette with one or more lifting eye suitable forinstalling or removing the cassette. The four bottom cornersof the cage rest within the frame in the tank. D6161

cake layer, n—layer comprised of particulate materials resid-ing on the upstream face of a membrane. D6161

calcium carbonate equivalents (mg/L as CaCO3) ,n—method for expressing mg/L as ion in terms of calciumcarbonate. Concentration in calcium carbonate equivalents iscalculated by multiplying concentration in mg/L of the ionby the equivalent weight of calcium carbonate (50) anddividing by the equivalent weight of the ion. (See Table 1 ofTerminology D6161). D6161

calcium hypochlorite, n—Ca (HCIO)2, a disinfection agent.D6161

calibration, n—in the analysis of water, the analysis ofstandards to develop a relationship between raw output of ananalytical system and analyte concentration.

DISCUSSION—Calibration can be done with traceable or non-traceablestandards. Calibration can be done with standards that are processedidentically to samples to produce “true” results, unbiased by recovery(of the standard), or calibration can be done with unprocessedstandards, typically in situations where recovery is not considered asignificant issue.

calibration, n—certified evaluation of the accuracy of ameasuring instrument as performed by its manufacturer or anindependent licensed or accredited third party. D6104

calibration, n—certified evaluation of the accuracy of ameasuring instrument as performed by its manufacturer or anindependent licensed or accredited third party. D6157

calibration—determining the instrument response to a knownamount of radioactive material. D7282

calibration blank, n—volume of water containing the sameacid matrix as the calibration standards. D1976

calibration blank, n—volume of water containing the sameacid matrix as the calibration standards. D5673

calibration curve, n—plot of the potential (emf) of a givenion-selective electrode cell assembly (ion-selective electrodecombined with an identified reference electrode) versus thelogarithm of the ionic activity (concentration) of a givenspecies. For uniformity, it is recommended that the potentialbe plotted on the ordinate (vertical axis) with the morepositive potentials at the top of the graph and that paA (-logactivity of the species measured, A) or pcA (-log concentra-tion of species measured, A) be plotted on the abscissa(horizontal axis) with increasing activity to the right.

IUPAC, D4127

calibration source (CS)—a known quantity of radioactivematerial, traceable to a national standards body, prepared forthe purpose of calibrating nuclear instruments. D7282

calibration standard, n—solution prepared from the primarydilution standard solution and stock standard solutions of theinternal standards and surrogate analytes. The calibrationstandards are used to calibrate the instrument response withrespect to analyte concentration. D5790

calibration standard, n—solution containing the analyte ofinterest at a known concentration either purchased from anexternal source or prepared in-house from materials ofknown purity or concentration, or both, and used to calibratethe measurement system. D5847

calibration standard (CAL), n—solution prepared from theprimary dilution standard solution and stock standard solu-tions of the internal standards and surrogate analytes. CALsolutions are used to calibrate the instrument response withrespect to analyte concentration. D5315

calibration standard (CAL), n—solution prepared from theprimary dilution standard solution and stock standard solu-tions of the internal standards and surrogate analytes. D5475

DISCUSSION—The CAL solutions are used to calibrate the instrumentresponse with respect to analyte concentration.

calibration standards, n—series of known standard solutionsused by the analyst for calibration of the instrument (prepa-ration of the analytical curve). D1976

calibration standards, n—series of known standard solutionsused by the analyst for calibration of the instrument (that is,preparation of the analytical curve). D5673

calibration stock solution, n—solution prepared from thestock standard solution(s) to verify the instrument responsewith respect to analyte concentration. D5673

calibration turbidity standard, n—turbidity standard that istraceable and equivalent to the reference turbidity standardto within statistical errors, including commercially prepared4000 NTU Formazin, stabilized formazin, and styrenedivi-nylbenzene (SDVB). These standards may be used to cali-brate the instrument. D6698

D1129 − 13

8

DISCUSSION—Calibration standards may be instrument specific.

calibration turbidity standard, n—a turbidity standard that istraceable and equivalent to the reference turbidity standardto within statistical errors, including commercially prepared4000 NTU Formazin, stabilized formazin (see 9.2.3), andstyrenedivinylbenzene (SDVB) (see 9.2.4). These standardsmay be used to calibrate the instrument. D6855

DISCUSSION—Calibration standards may be instrument specific.

calibration verification standards, n—defined standards usedto verify the accuracy of a calibration in the measurementrange of interest. These standards may not be used toperform calibrations, only calibration verifications. Includedstandards are optomechanical light scatter devices, gel-likestandards, or any other type of stable liquid standard. D6698

DISCUSSION—Calibration verification standards may be instrumentspecific.

calibration verification standards, n—defined standards usedto verify the accuracy of a calibration in the measurementrange of interest. These standards may not be used toperform calibrations, only calibration verifications. Includedstandards are optomechanical light scatter devices, gel-likestandards, or any other type of stable liquid standard. D6855

DISCUSSION—Calibration verification standards may be instrumentspecific.

calibrations:— D3864laboratory check sample for flow-through systems,

n—calibration curve calculated from withdrawn samples oradditional standards that may be spiked or diluted and analyzedusing the appropriate laboratory analyzer. D3864

line sample calibration, n—coincidental comparison of aline sample and adjustment of a continuous analyzer to thecompared laboratory analyzer or a second continuous analyzer.

D3864

multiple standard calibration, n—where the calibrationcurve is calculated from a series of calibration standardscovering the range of the measurements of the sample beinganalyzed. D3864

probe calibration, n—where the probe is removed from thesample stream and exposed to a calibration solution and theanalyzer is adjusted to indicate the appropriate value.Alternately, two probes are exposed to the same solution andthe on-line analyzer is adjusted to coincide with the pre-calibrated laboratory instrument. D3864

reference sample calibration, n—coincidental comparison ofa reference sample and adjustment of a continuous analyzer tothe compared laboratory analyzer results. D3864

capillary ion electrophoresis, n—electrophoretic technique inwhich a UV-absorbing electrolyte is placed in a 50- to 75-µmfused silica capillary. Voltage is applied across the capillarycausing electrolyte and anions to migrate towards the anodeand through the capillary’s UV detector window. Anions areseparated based upon the their differential rates of migrationin the electrical field. Anion detection and quantitation arebased upon the principles of indirect UV detection. D6508

carbonate hardness, n—hardness in a water caused by car-bonates and bicarbonates of calcium and magnesium. Theamount of hardness equivalent to the alkalinity formed anddeposited when water is boiled. In boilers, carbonate hard-ness is readily removed by blowdown. D6161

carryover, n—contamination of a subsequent sample by aprevious sample, typically a result of incomplete cleaning ofa reused test kit component. D5463

cartridge, n—see spiral-wound cartridge. D6161

cassette, n—assembly of membrane elements (or modules),membrane aerators, air and permeate manifolds, and hard-ware in the cage; this is how the membranes are installed orremoved from the process tank. D6161

catalyst, n—substance whose presence initiates or changes therate of a chemical reaction, but does not itself enter into thereaction. D6161

cathode, n—negative electrode. D6161

cation, n—positively charged ion. D6161

cation conductivity, n—a conductivity measurement per-formed on water after cations have been exchanged forprotons using cation exchange media.

cation conductivity, n—parameter obtained by conditioning asample by passing it through a hydrogen form cation ionexchange resin column and then measuring its electrolyticconductivity, on-line. D6504

cation-exchange material, n—a material capable of the re-versible exchange of positively charged ions.

cation-exchange material, n—ion-exchange material capableof the reversible exchange of positively charged ions. D2187

cation-exchange material, n—ion-exchange material capableof the reversible exchange of positively charged ions. D4548

cation exchange material, n—material capable of the revers-ible exchange of positively charged ions. D6161

cation exchange membrane, n—membrane containing fixedanionic charges and mobile cations that can be exchangedwith other cations present in an external fluid in contact withthe membrane. D6161

cationic polyelectrolyte, n—polymer containing positivelycharged groups used for coagulation/flocculation, usuallydimethyl-aminoethyl methacrylate or dimethyl-aminoethylacrylate. See polyelectrolyte. D6161

caustic embrittlement, n—a form of metal failure that occursin steam boilers at riveted joints and at tube ends, thecracking being predominantly intercrystalline.

cell, n—independently fed chamber formed by two adjacention exchange membranes, or by a membrane and an adjacentelectrode. D6807

cell constant, n—ratio of the length of the path, L (cm) and thecross-sectional area of the solution, A (cm2), between the

D1129 − 13

9

electrodes of a conductivity/resistivity cell, with units ofcm-1. In high-purity water measurements, the cell constant isnormally between 0.001 and 0.1 cm-1 to prevent electricalinterference. This is lower than the 1 cm-1 of the standardcentimetre cube and is taken into account by direct readinginstrument ranges that are matched with specific cellconstants. D5391

cell monolayer, n—single layer of cells grown on a glass orplastic surface to which they are securely attached. D5244

cellulose, n—amorphous carbohydrate (C6H10O5) that is theprincipal constituent of wood and plants. D6161

cellulose acetate (CA), n—in the broad sense, any of severalesters of cellulose and acetic acid. D6161

celsius (°C), n—designation of the degree on the InternationalPractical Temperature Scale. Formerly called centigrade,°C = °K minus 273.15. K = Kelvin. °C = (°F –32) * 0.556.

D6161

censored measurement, n—measurement that is not reportednumerically nor is reported missing but as a nondetect or aless-than, for example, “less than 0.1 ppb.” The formermeans that an algorithm in the measurement system deter-mined that the measurement should not be reported numeri-cally for one of two reasons: either it was considered notsufficiently precise or accurate, or the identification of theanalyte was suspect. A reported less-than may have the samemeaning, but it also implies (perhaps erroneously) that anyconcentration greater than or equal to the accompanyingvalue (for example, 0.1 ppb) can be measured and will bereported numerically. D6091

censored measurement, n—measurement that is not reportednumerically nor is reported missing, but is stated as anondetect or a less-than (for example, “less than 0.1 ppb”).There are two reasons why the measurement may not bereported numerically. Either the measurement was consid-ered insufficiently precise or accurate (these kinds of datashould not be censored), or the identification of the analytewas suspect (these kinds of data should be censored). See6.2.3.1 of Practice D6512. A reported “ less than” may havethe same meaning as a non-reported measurement, but areported “less than” also implies (perhaps erroneously) thatany concentration greater than or equal to the accompanyingvalue (for example, 0.1 ppb) can be measured, and will bereported numerically. D6512

centigrade, n—since 1948, now called Celsius, a temperaturescale. D6161

centroid, n—center of mass of the dye response curve calcu-lated as outlined by Parker and Hunt.3 D5613

ceramic membrane, n—generally a glass, silica, alumina, orcarbon-based membrane. Generally used in micro and ultra-filtration. They tend to withstand high temperatures and wide

pH ranges and be more chemically inert than polymericmembranes. D6161

certified reference material, n—reference material, accompa-nied by a certificate, one or more of whose property valuesare certified by a procedure that established its traceability toan accurate realization of the unit in which the propertyvalues are expressed and for which each certified value isaccompanied by an uncertainty at a stated level of confi-dence. ISO Guide 30:1992, D6568

DISCUSSION—There is significant variation in the overall quality ofcommercially available Certified Reference Materials and cautionshould be used when choosing Certified Reference Materials. UsePractice D6362 to provide guidance as to what information needs to beincluded on certificate of a certified reference material.

chain of custody, n—documented accountability of eachsample, that is, date, time, and signature of each recipientwhen the sample changes hands, from the time of collectionuntil the requirement for each sample is terminated. D4489

channel, n—natural or artificial waterway that periodically orcontinuously contains moving water. D4410

channel-fill deposits, n—deposits of sediment within achannel, partly or completely filling the channel. Suchmaterials accumulate where the transporting capacity hasbeen insufficient to remove it as rapidly as it has beendelivered. D4410

channeling, v—unequal flow distribution in the desalinationbundle or filter bed. D6161

characteristic ion, n—usually the primary ion in the massspectrum used to measure response for quantitation pur-poses. When there are interferences in the mass chromato-gram of a primary ion, a secondary characteristic ion must beused for quantitation. D4128

charge-mosaic membranes, n—synthetic membranes com-posed of two-dimensional or three-dimensional alternatingcation and anion exchange channels throughout the mem-brane. D6161

check valve, n—device (see Fig. 1) mounted atop an open-barrel core sampler. As the sampler moves down throughwater and sediment, the valve remains open to allow water toflow up through the barrel. When downward motion stops,the valve closes. During retrieval, the valve remains closedand creates suction that holds the core inside the barrel.

D4823

check valve, n—valve that will allow water to pass in onedirection but will close and prevent flow in the oppositedirection. D6161

chelating agent, n—sequestering or complexing agent that, inaqueous solution, renders a metallic ion inactive through theformation of an inner ring structure with the ion. D6161

chemical, n—in the analysis of water, a mono-molecular ormono-elemental material of acceptable purity, manufacturedfor application in conducting analyses.

3 Parker, G. W., and Hunt, G. S., “Initial Assessment of Time-of-Travel ThroughGulf Island Pond and the Lower Androscoggin River, Maine,” U.S. GeologicalSurvey Water-Resources Investigations Report 83-4020, 1983.

D1129 − 13

10

chemical feed pump, n—pump used to meter chemicals, suchas chlorine of polyphosphate, into a feed water supply.

D6161

chemical oxygen demand—see COD. D6161

chemical suppressor device, n—device that is placed betweenthe analytical columns and the detector. Its purpose is toinhibit detector response to the ionic constituents in theeluent, so as to lower the detector background and at thesame time enhance detector response to the ions of interest.

D4327

chemiluminescence, n—generation of light by a chemicalreaction. D6592

chloramines, n—combination of chlorine and ammonia inwater which has bactericidal qualities for a longer time thandoes free chlorine. D6161

chlorine, n—chemical used for its qualities as a bleaching oroxidizing agent and disinfectant in water purification. D6161

chlorine demand, n—amount of chlorine that must be addedto a unit volume of water under specified conditions of pH,temperature, and contact time to completely react with allchlorine-reactable substances in the water. It is defined as thedifference between the amount of chlorine applied and theamount of free chlorine remaining at the end of the contactperiod. D1291

chlorine demand, n—amount of chlorine used up by reactingwith oxidizable substances in water before chlorine residualcan be measured. D6161

chlorine, combined available, n—residual chlorine combinedwith ammonia nitrogen or nitrogenous compounds.

chlorine, free available, n—the hypochlorite ions (OCl −),hypochlorous acid (HOCl) or the combination thereof pres-ent in water.

chlorine, free available, n—chlorine (Cl2), hypochlorite ions(OCl–), hypochlorous acid (HOCl), or the combinationthereof present in water. D6161

chlorine requirement, n—the amount of chlorine required toachieve, under specified conditions, the objectives of chlo-rination.

chlorine requirement, n—amount of chlorine that shall beadded to a unit volume of water under specified conditions ofpH, temperature, and contact time to achieve the objectivesof chlorination. D1291

chlorine residual, n—the amount of available chlorine presentin water at any specified time.

chlorine, residual, n—amount of available chlorine present inwater at any specified time. D6161

chlorine, total available, n—sum of free available chlorineplus chloramines present in water. D6161

chlorinity, n—weight of silver ion (g) required to precipitatecompletely the halides in 0.3285 kg of water (g/kg). D1141

chloroplatinate unit—see CPU. D6161

chlorosity, n—the concentration of the dissolved chlorideequivalent in water at 20°C.

citric acid, n—C3H4(OH)(CO2H)3, membrane-cleaningchemical. D6161

clarifier, n—tank in which precipitate settles and supernatantoverflows, a liquid-solids separation unit using gravity toremove solids by sedimentation. D6161

Clark degree, n—number of grains of substance per oneBritish imperial gallon of water expressed CaCO3. Concen-tration in Clark or English degree is calculated by dividingconcentration in calcium carbonate equivalents by 14.3. Onegrain weighs 1/7000 lb and one imperial gallon of waterweighs 10 lbs at 25°C. (See Table 1 of Terminology D6161.)

D6161

classic gully, n—channel that is formed by gully erosion and isnot interrupted by mechanical tillage operations to fill theresulting void. Gully depth can exceed 30 m. (See gullyerosion.) D4410

clay size (fluvial sediment), n—0.00024 to 0.004 mm indiameter. D4410

cleaning-in-place—see CIP. D6161

clear well, n—collection basin that houses filtered or clarifiedwater. D6161

Clostridium perfringens, n—in this test method, C. perfrin-gens is defined as an obligate anaerobic gram-positive, sporeforming, nonmotile bacillus, 0.9–1.3 by 3.0–9.0 µm in sizethat ferments sucrose, ferments lactose with stormy gas

NOTE 1—Dark bands represent stiff sediments; light bands representplastic sediments. As coring proceeds, sediment below the barrel moveslaterally away from the cutting edge and plastic sediments inside the barrelare compressed. “A” is the core’s length and “B” is the barrel’spenetration depth.

NOTE 2—Source: Weaver, P. P. E., and Schultheiss, P. J., “Detection ofRepenetration and Sediment Disturbance in Open-Barrel Gravity Cores,”Journal of Sedimentary Petrology, Vol 53, No. 2, June 1983, pp. 649–654.

FIG. 1 Deformations Caused by Open-Barrel Core Samplers

D1129 − 13

11

production, does not ferment cellobiose, and produces acidphosphatase. C. perfringens also produces toxins that causegas gangrene and gastroenteritis. D5916

coagulant, n—chemical added in water and wastewater appli-cations to cause destablization of suspended particles andsubsequent formation of flocs that adsorb, entrap, or other-wise bring together suspended matter that is so fine, it isdefined as colloidal. Compounds of iron and aluminum aregenerally used to form flocs to allow removal of turbidity,bacteria, color, and other finely divided matter from waterand waste water. D6161

coagulation, n—agglomeration of colloidal or finely dividedsuspended matter caused by the addition to the liquid of anappropriate chemical coagulant, by biological processes, orby other means (see also agglomeration). D4410

coalescing, v—separation of mixtures of immiscible fluids(such as oil and water) based on different specific gravitiesand surface tensions. Coalescence occurs whenever two ormore droplets collide and remain in contact and then becomelarger by passing through a coalescer. The enlarged dropsthen separate out of solution more rapidly. D6161

cobble size (fluvial sediment), n—64 to 256 mm in diameter.D4410

co-current flow, n—flow pattern through a membrane in whichthe fluids on the upstream and downstream sides of themembrane move parallel to the membrane surface and in thesame directions. (See FIG 1 of Terminology D6161.) D6161

chemical oxygen demand (COD), n—amount of oxygenrequired under specified test conditions for the oxidation ofwater borne organic and inorganic matter. D6161

cohesive sediments, n—that material whose resistance toinitial movement or erosion depends upon the strength of thebond between particles. D4410

coliform bacteria, n—particular group of bacteria primarilyfound in human and animal intestines and wastes. D6161

coliphage, n—bacterial virus capable of plaquing on thewide-range E. coli host strain used in this assay. D6734

collaborator, n—technically competent body (organization orfirm, public or private) that undertakes aspects of themanufacture, or characterization, of the (certified) RM onbehalf of the RM producer, either on a contractual (as asubcontractor) or voluntary basis. D6808

collocated samples, n—independent samples collected asclose as possible to the same point in space and time andintended to be identical. D5612

colloid, n—substance of very fine particle size, typicallybetween 0.1 and 0.001 µm in diameter suspended in liquid ordispersed in gas. A system of at least two phases, includinga continuous liquid plus solid, liquid or gaseous particles sosmall that they remain in dispersion for a practicable time.

D6161

colloidal suspension, n—any material in suspension (forexample, silica) with a nominal particle size less than 100nm. D5544

colloids (fluvial sediment), n—smaller than 0.00024 mm indiameter. D4410

colluvial deposits, n—that material accumulated along valleymargins by mass movements from the adjacent hillsides.

D4410

colony forming unit (CFU), n—unit used in the measure oftotal bacterial count (TBC). D6161

combination electrode, n—electrochemical apparatus that in-corporates an ion-selective electrode and a reference elec-trode in a single assembly thereby avoiding the need for aseparate reference electrode. IUPAC, D4127

combined available chlorine—see CAC . D6161

combined residual chlorine, n—residual consisting of chlo-rine combined with ammonia nitrogen or nitrogenous com-pounds. D1253

compaction, n—in crossflow filtration, the result of appliedpressure and temperature compressing a polymeric mem-brane which may result in a decline in flux. D6161

completely mixed (perfectly mixed) flow, n—flow through amembrane module in which fluids on both the upstream anddownstream sides of the membrane are individually wellmixed. (See Fig. 1 of Terminology D6161.) D6161

complexometric titration—see titration . D4127

composite membrane, n—membrane having two or morelayers with different physical or chemical properties. Mem-brane manufactured by forming a thin desalinating barrierlayer on a porous carrier membrane. D6161

composite sample, n—a combination of two or more samples.

composite sample, n—sample formed by combining two ormore individual samples or representative portions of thesamples. D4410

composite sample—a series of grab samples integrated into asingle sample or a sample collected at specific time intervalsand integrated into a single sample. The goal of a compositesample is to characterize a process weighted average inproportion to process parameters. D3370

compostable plastic, n—plastic that undergoes degradation bybiological processes during composting to yield CO2, water,inorganic compounds, and biomass at a rate consistent withother known compostable materials and leave no visible,distinguishable or toxic residue. D6888

composting, v—managed process that controls the biologicaldecomposition and transformation of biodegradable materi-als into a humus-like substance called compost: the aerobicmesophilic and thermophilic degradation of organic matterto make compost; the transformation of biologically decom-posable material through a controlled process of biooxida-tion that proceed through mesophilic and thermophilic

D1129 − 13

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phases and results in the production of carbon dioxide,water, minerals, and stabilized organic matter (compost orhumus). D6888

DISCUSSION—Composting uses a natural process to stabilize mixeddecomposable organic material recovered from municipal solid waste,yard trimmings, biosolids (digested sewage sludge), certain industrialresidues, and commercial residues.

compression rate, n—rate at which the air is compressed in thesample container and is a function of the speed at which thesampler is lowered in the sampling vertical. D6326

concentrate, n—stream exiting a crossflow membrane devicethat has increased concentration of solutes and particles overthe feed stream; portion of the feed stream that does not passthrough the membrane. The stream in which dissolved solidsor particulates, or both, are concentrated in a membraneseparation process. D6161

concentrate recycle, n—technique for improving recovery inwhich a fraction of the concentrate is recycled through themembrane system. D6161

concentrate, reject, or brine, n—that portion of feed that doesnot pass through the membrane. D5089

concentrate (reverse osmosis), n—the residual portion of anaqueous solution applied to a membrane.

concentration, n—actual amount of a substance in a givenvolume of solution. When measuring ionic concentrations byelectrode, a distinction is made between the concentration ofthe free, unbound ion, and total concentration that includesions bound to complexing agents. D4127

concentration factor (CF), n—ratio of the concentration of acomponent in the retenate (concentrate, brine) to the con-centration of the same component in the feed: D6161

CF 5CB~brinewater concentration!CF~feedwater concentration!

51

1 2 concentration ~approximation!

concentration of sediment (by mass), n—ratio of the mass ofdry sediment in a water-sediment mixture to the mass of themixture. D4410

concentration polarization, n—increase of the solute concen-tration over the bulk feed solution that occurs in a thinboundary layer at the feed side of the membrane surface,resulting from the removal of the solvent. Concentrationprofile that has a higher level of solute nearest to theupstream membrane surface compared with the more-or-lessmixed bulk fluid far from the membrane surface. D6161

concentration, sediment, n—ratio of the mass of dry sedimentin a water-sediment mixture to the volume of the water-sediment mixture. Refer to Practice D3977. D4411

concentration standard, n—standardizing solution whosevalue is reported in terms of total concentration of the ion ofinterest. If the electrode is calibrated using pure-concentration standards and measurements made on un-treated samples, results must be corrected for the sample

ionic strength and the presence of complexing agents. Morecommonly, a reagent is added to all standards and samplesbefore measurement to fix the ionic strength, thus avoidingthe need for correction. D4127

concentration (volume), n—ratio of the volume of dry sedi-ment to the volume of the water-sediment mixture. D4410

concentrator column, n—ion exchange column used to con-centrate the ions of interest and thereby increase methodsensitivity. D5542

concentrator column, n—ion exchange column used to con-centrate the ions of interest and thereby increase methodsensitivity. D5996

condensation particle counter (CPC), n—instrument fordetecting very small aerosol particles in a size range fromapproximately 10 nm to 2 to 3 µm. The CPC cannotdifferentiate between particles of varying size within thissize range; it reports the number of particles with a sizegreater than that defined by its detection efficiency curve.Detection is independent of particle composition. D5544

conductivity, n—property of a substance’s (in this case, waterand dissolved ions) ability to transmit electricity. The inverseof resistivity. Measured by a conductivity meter, and de-scribed in microsiemens/cm or micromhos/cm, µS/cm.

D6161

confirmed identification, n—to confirm a tentativeidentification, both the GC retention time and the massspectrum of a compound shall uniquely match those of areference compound as demonstrated by co-injection of theauthentic standard with the tentatively identified compound.

D4128

contaminant, n—any foreign substance present that will ad-versely affect performance or quality. D6161

contaminated run-off, n—rain water that has collected oilycontaminants from the surfaces it came in contact with andmay appear in the influent to a separator. Unlike a release,the level of contamination in this case is much lower. D6104

contaminated run-off, n—rain water that has collected oilycontaminants from the surfaces it came in contact with andmay appear in the influent to a separator. Unlike a release,the level of contamination in this case is much lower. D6157

continuing instrument quality control—measurements takento ensure that an instrument responds in the same mannersubsequent to its calibration. D7282

continuous deionization, n—deionization process that doesnot require regular interruptions in service to discharge ionicmaterials collected from the water being processed. D6161

continuous electrodeionization (CEDI) device, n—devicethat removes ionized and ionizable species from liquidsusing electrically active media and using an electricalpotential to influence ion transport in which the ionictransport properties of the active media are a primary sizingparameter. CEDI devices typically comprise semipermeable

D1129 − 13

13

ion exchange membranes and permanently charged ionexchange media. Examples include continuous deionization,electrodiaresis, and packed-bed or filled-cell electrodialysis.

D6807

continuous electrodeionization (CEDI) device—a devicethat removes ionized and ionizable species from liquidsusing electrically active media and using an electricalpotential to influence ion transport, where the ionic transportproperties of the active media are a primary sizing param-eter. The CEDI devices typically comprise semipermeableion-exchange membranes and permanently charged ion-exchange media. Examples include continuous deionization,electrodiaresis, and packed-bed or filled-cell electrodialysis.

D6529

continuous wave system, n—electronic positioning system inwhich the signal transmitted between the transmitter andresponder stations travels as a wave having constant fre-quency and amplitude. D5906

contracted weirs, n—contractions of thin-plate weirs refer tothe widths of weir plate between the notch and the sidewallsof the approach channel. In fully contracted weirs, the ratioof the notch area to the cross-sectional area of the approachchannel is small enough for the shape of the channel to havelittle effect. In suppressed (full-width) rectangular weirs, thecontractions are suppressed, and the weir crest extends thefull width of the channel. D5640

control, n—physical properties of a channel that determine therelationship between the stage and discharge of a location inthe channel. D5674

control analyses, n—the determination of specific parametersused as criteria for proper operation of a system.

control block, n—group of devices having a common pipingand control system. D6161

conversion (Y), n—product water flow rate divided by feedwater flow rate. Also called recovery; given as fraction ordecimal. See recovery. D6161

conversion factors, n—see Table 1 of Terminology D6161.D6161

conveyance (K), n—measure of the carrying capacity of achannel and has dimensions of cubic feet per second or cubicmetres per second. Conveyance is computed as follows:

D5130

K 51.486

nAR2/3

where:n = the Manning roughness coefficient,A = the cross-section area, ft2 (m2), andR = the hydraulic radius, ft (m).1.486 = 1.00 SI unit

conveyance, (K), n—measure of the carrying capacity of achannel cross section, or parts of a cross section, and hasunits of cubic feet per second or cubic metres per second.Conveyance is computed as follows: D5129

K 5*1.486

nAR2/3

where:n = the Manning roughness coefficient,A = the cross-section area, ft2 (m2),R = the hydraulic radius, ft (m), and*in SI units = 1.0

The following subscripts refer to specific conveyances forparts of a cross section:

Ka, Kb = conveyances of parts of the approach section toeither side of the projected bottom width of thecontracted section (see Fig. 2 of D5129). Kd isalways the smaller of the two,

Kd = conveyance at the upstream end of the dikes,Ki = conveyance of subsection i,Kq = conveyance of the part of the approach section

corresponding to the projected bottom-width, andKT = total conveyance of cross section.

conveyance (K), n—measure of the carrying capacity of achannel and having dimensions of cubic feet per second.

D5243DISCUSSION—Conveyance is computed as follows:

K 51.486

nR2/3A

where:n = the Manning roughness coefficient,A = the cross section area, in ft2 (m2), andR = the hydraulic radius, in ft (m).1.486 = 1.00 SI unit

conveyance (K), n—measure of the carrying capacity of achannel without regard to slope and has dimensions of cubicfeet per second. Conveyance is computed as follows: D5388

K 51.49

nAR2/3

core, n—vertical column of sediment cut from a parent deposit.D4823

core catcher, n—device (see Fig. 2) that grips and supports thecore while the sampler is being pulled from the sediment andhoisted to the water surface. D4823

core conveyor, n—device (see Fig. 3) for reducing frictionbetween a core and the inside surface of a core barrel. D4823

core-barrel liner, n—rigid, thin-wall tube mounted inside thebarrel of a core sampler. During the core-cutting process,sediment moves up inside the liner. D4823

core sampler, n—instrument for collecting cores. D4823

corrosion, n—deterioration of the metal by reaction with itsenvironment. D4778

corrosion product sampler, n—device used to collect inte-grated samples of filterable and (as an option) nonfilterablematter. It consists of a flow totalizer that accurately measuresthe amount of sample passing through the device and a

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14

0.45-µm pore size membrane filter. Adding a second filter forion exchange resin impregnated membranes allows forcollecting nonfilterable matter. D6301

corrosion products, n—products that result from chemical orelectrochemical reaction between a metal and its environ-ment.

corrosion products, n—products that result from chemical orelectrochemical reaction between a metal and its environ-ment. D6161

corrosion products—a result of chemical or electrochemicalreaction between a metal and its environment. D887

cosine response, n—ability of a meter, placed at an angle to theoncoming flow, to sense the component of velocity parallelto its axis. D5089

counter background, n—in the measurement of radioactivity,the counting rate resulting from factors other than theradioactivity of the sample and reagents used. D1890

DISCUSSION—Counter background varies with the location, shieldingof the detector, and the electronics; it includes cosmic rays, contami-nating radioactivity and electrical noise.

counter beta-particle efficiency, n—in the measurement ofradioactivity, that fraction of beta particles emitted by asource which is detected by the counter. D1890

counter-current flow, n—flow through a membrane module inwhich the fluid on the upstream and downstream sides of themembrane move parallel to the membrane surface but in theopposite direction. (See Fig. 1 of Terminology D6161.)

D6161

counter efficiency, n—in the measurement of radioactivity,that fraction of the disintegrations occurring in a sourcewhich is detected by the counter. D1890

crest, n—bottom of the overflow section or notch of arectangular weir. D5242

crest, n—horizontal plane surface of the weir. D5614

crest, n—in rectangular thin-plate weirs, the horizontal bottomof the overflow section; in broad-crested weirs and flumes,the plane, level floor of the flow section. D5640

criterion of detection, n—minimum quantity that shall beobserved before it can be stated that a substance has beendiscerned with an acceptable probability that the statement istrue (see Practice D4210). D4841

critical flow, n—open channel flow in which the energy,expressed in terms of depth plus velocity head, is a minimumfor a given flow rate and channel. The Froude number isunity at critical flow. D5614, D4410

critical flow, n—open channel flow in which the energyexpressed in terms of depth plus velocity head, is a minimumfor a given flowrate and channel. The Froude number isunity at critical flow. D5390

critical flow, n—open channel flow in which the energy,expressed in terms of depth plus velocity head, is a minimumfor a given flow rate and channel. The Froude number isunity at critical flow. D5614

NOTE 1—(a) The leaves separate during penetration and then closeduring retrieval. Strips of gauze can be woven around the leaves toprovide additional support. (See Note 2.) (b) The lever trips down duringretrieval to release the spring and twist the fabric sleeve shut. (See Note3.) (c) The cupped plate drops during retrieval to block the entrance andsupport the core. (See Note 2.) (d) The lever releases the spring-loadedblade which pivots downward to hold the core. (See Note 2.)

NOTE 2—Source: Sachs, P. L., and Raymond, S. O., “A New Unat-tached Sediment Sampler,” Journal of Marine Research, Vol 23, 1965, pp.44–53.

NOTE 3—Source: Bouma, A. H., Methods for the Study of SedimentaryStructures, Wiley-Interscience, New York, NY, 1969, pp. 301–378.

FIG. 2 Core Catchers

NOTE 1—(a) Strips of metal foil slide up through the core barrel as thecutting edge advances downward. (See Note 2.) (b) The plastic sleeveunfolds from pleats stored near the cutting edge. This sleeve surrounds thecore as the barrel moves down. (See Note 3.)

NOTE 2—Source: Carrigan, P. H., Jr., “Inventory of Radionuclides inBottom Sediment of the Clinch River Eastern Tennessee,” U.S. GeologicalSurvey Professional Paper 433-I, U.S. Government Printing Office,Washington, DC, 1969.

NOTE 3—Source: Sachs, P. L., and Raymond, S. O., “A New Unat-tached Sediment Sampler,” Journal of Marine Research, Vol 23, 1965, pp.44–53.

FIG. 3 Core Conveyors

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15

critical flow, n—open-channel flow in which the energy,expressed in terms of depth plus velocity head, is a minimumfor a given flow rate and channel. D5640

DISCUSSION—The Froude number is unity at critical flow.

critical level, n—with a specified level of confidence (forexample, 95 % or 99 %), the lowest result that indicates thepresence of an analyte.

DISCUSSION—Specifically, the lowest result that is statistically differ-ent from zero. This term originates with the publications of LloydCurrie (Anal. Chem. 40 (1968) 586; ISO 11843–1:1997). A criticallevel is dependent on the analyte of interest, the analytical method, andthe matrix. The U.S. Environmental Protection Agency’s MethodDetection Limit (MDL) (Federal Register 40 CFR, Part 136, AppedixB, 7–1–99 edition) is an example of a critical level.

cross flow, n—flow through a membrane module in which thefluid on the upstream side of the membrane moves parallel tothe membrane surface and the fluid on the downstream sideof the membrane moves away from the membrane in thedirection normal to the membrane surface. (See Fig. 1 ofTerminology D6161.) D6161

crossflow membrane filtration, n—separation of the compo-nents of a fluid by semipermeable membranes through theapplication of pressure and flow parallel to the membranesurface. Includes the processes of reverse osmosis,utrafiltration, anofiltration, and microfiltration. D6161

cross-section area (A), n—area of the water below thehigh-water surface elevations that are computed by assum-ing a straight-line interpolation between elevations on eachbank. The area is computed as the summation of the productsof mean depth multiplied by the width between stations ofthe cross section. D5130

cross-section area (A), n—area at the water below the water-surface elevation that it computed. The area is computed asthe summation of the products of mean depth multiplied bythe width between stations of the cross section. D5388

cross sectional area (A), n—area occupied by the water.D5243

cross sections (numbered consecutively in downstreamorder), n—representative of a reach of channel and arepositioned as nearly as possible at right angles to thedirection of flow. They must be defined by coordinates ofhorizontal distance and ground elevation. Sufficient groundpoints must be obtained so that straight-line connection ofthe coordinates will adequately describe the cross-sectiongeometry. If major breaks in the high-water profile areevident, cross sections should be located at the breaks.

(D5130

cross sections (numbered consecutively in down-streamorder), n—The approach section, Section 1, is located oneculvert width upstream from the culvert entrance. CrossSections 2 and 3 are located at the culvert entrance and theculvert outlet, respectively. Subscripts are used with symbolsthat represent cross sectional properties to indicate thesection to which the property applies. For example, A1 is thearea of Section 1. Items that apply to a reach between two

sections are identified by subscripts indicating both sections.For example, hf1-2 is the friction loss between Sections 1 and2. D5243

cross sections (numbered consecutively in downstreamorder), n—representative of a reach and channel and arepositioned as nearly as possible at right angles to thedirection of flow. They must be defined by coordinates ofhorizontal distance and ground elevation. Sufficient groundpoints must be obtained so that straight-line connection ofthe coordinates will adequately describe the cross-sectiongeometry. D5388

crud deposition, n—deposition on interior surfaces of sampletubing or other hardware of fine insoluble particles of ironoxides and other byproducts of metallic corrosion that arepresent throughout the system. The term “crud” is generallyused for all types of fouling. D5540

cryptosporidium, n—waterborne protozoan that forms cystsand causes acute gastrointestinal illness in humans. D6161

crystal membrane or solid-state electrode membrane—seemembrane. D4127

current efficiency, n—ratio, expressed in percent, of the nettransfer of ionized and ionizable solutes per unit cell withina CEDI device, expressed in chemical equivalents trans-ferred per unit time, to the number of coulombs transferredfrom an external DC power source to each electrode pair,expressed in faradays per unit time. Calculation of currentefficiency is described in 9.2 of Test Method D6807. D6807

current efficiency—the ratio, expressed in percent, of the nettransfer of ionized and ionizable solutes per unit cell withina CEDI device, expressed in chemical equivalents trans-ferred per unit time, to the number of coulombs transferredfrom an external dc power source to each electrode pair,expressed in faradays per unit time. Calculation of currentefficiency is described in 9.2. D6529

current meter, n—instrument used to measure, at a point,velocity of flowing water. D3858

current meter, n—instrument used to measure the speed orvelocity of flowing water at a point. D4409

custody, n—physical possession or control. A sample is undercustody if it is in possession or under control so as to preventtampering or alteration of its characteristics. D4840

cycle time, n—interval between repetitive sample introduc-tions in a monitoring system with discrete sampling. D3864

Dalton, n—arbitrary unit of molecular weight, one twelfth themass of the nuclide of carbon 12. D6161

data acquisition equipment, n—see monitoring system.D3864

data defensibility, n—process that provides sufficientassurance, both legal and technical, that assertions madeabout a sample and its measurable characteristics can besupported to an acceptable level of certainty. See Appendix

D1129 − 13

16

X1 of Guide D4840 for a discussion of the elements of a datadefensibility process. D4840

data quality objectives (DQOs), n—statements on the level ofuncertainty that a decision maker is willing to accept in theresults derived from environmental data (seeQAMS-500/80). D5612

data traceability, n—the ability to verify data by havingaccess to, and documentation of, all prior information usedto generate it and needed for its interpretation.

datum, n—plane that represents a zero or some definedelevation. D5413

datum, n—level plane that represents zero elevation. D5674

dead end filtration, n—process in which water is forcedthrough a media which captures the retained particles on andwithin it, where the process involves one influent and oneeffluent stream. D6161

dead end flow, n—flow through a membrane module in whichthe only outlet for the upstream fluid is through the mem-brane. (See Fig. 1 of Terminology D6161.) D6161

deaerator, n—device to remove air from water. D6161

debris, n—as applied to geologic debris flows, a mixture ofloose, poorly-sorted rock fragments or soil material, or both,potentially ranging from clay to boulder-size particles thatmay include fragmental organic matter and other exoticdetritus. D4410

decarbonator, n—device to remove carbon dioxide fromwater. D6161

degasification, n—process of removing dissolved gasses fromwater. D6161

degradable plastic, n—plastic designed to undergo a signifi-cant change in its chemical structure under specific environ-mental conditions, resulting in a loss of some properties thatmay be measured by standard test methods appropriate to theplastic and the application in a period of time that determinesits classification. D6888

degradation, n—geologic process by which stream beds, floodplains, the bottoms of other water bodies, and other landsurfaces are lowered in elevation by the removal of materialby fluids. D4410

deionization (DI), n—removal of ions from a solution by ionexchange. D6161

delivery rate, n—use sediment delivery ratio or sedimentyield, whichever is meant. D4410

delta, n—sediment deposit formed where moving water isslowed by a slower moving body of water. D4410

demineralization, n—process of removing minerals fromwater. D6161

denitrification, n—aqueous nitrate reduction or removal.D6161

dense (nonporous) membrane, n—membrane with no detect-able pores. D6161

density, n—mass of a substance per unit volume, ρ in kg/L orkg/m3. Use ρs for density of solid particles, ρw for water, ρdfor dry sediment with voids, ρsat for saturated sediment, ρwetfor wet sediment, and ρb for submerged sediment (buoyantweight). D4410

density current, n—movement of one fluid under, through, orover another fluid of differing density. D4410

deposition, n—the chemical, mechanical, or biological pro-cesses through which sediments accumulate in a restingplace. D4410

depth (y), n—depth of flow at a cross section. Subscriptsdenote specific cross section depths as follows: D5129

y1 = depth of flow in cross section 1 (approach section) andy3 = depth of flow in cross section 3 (contracted section).

depth-integrated sample, n—discharge-weighted (velocity-weighted) sample of water-sediment mixture collected at oneor more verticals in accordance with the technique of depthintegration; the discharge of any property of the sampleexpressible as a concentration can be obtained as the productof the concentration and the water discharge represented bythe sample. D4410

depth-integrated sample, n—water sample collected in such amanner as to be representative of the water mixture movingin the river in the vicinity of the sampler at a single verticalin a cross section. D5613

depth-integrating sediment sampler, n—device that collectsa representative water-sediment mixture at all points alongthe sampling vertical. D4410

depth-integrating suspended sediment sampler,n—instrument capable of collecting a water-sediment mix-ture isokinetically as the instrument is traversed across theflow; hence, a sampler suitable for performing depthintegration. D4411

depth integration, n—method of sampling at every pointthroughout a given depth (the sampled depth) whereby thewater-sediment mixture is collected isokinetically so that thecontribution from each point is proportional to the streamvelocity at the point. This process yields a sample withproperties that are discharge weighted over the sampleddepth. Ordinarily, depth integration is performed by travers-ing either a depth- or point-integrating sampler vertically atan acceptably slow and constant rate; however, depth inte-gration can also be accomplished with vertical slot samplers.

D4410

depth-integration, n—method of sampling at every pointthroughout a sampled depth whereby the wa